1. Field of the Invention
This application relates to improved subterranean fluid sampling systems and improved subterranean fluid sampling methods. More particularly, it concerns such systems and methods based on direct push technology.
2. Description of the Prior Art
The sampling of subterranean waters or other fluids is required for a variety of reasons, investigation of ground water contaminant plumes being a current major demand for such sampling operations.
Subterranean sampling is an ancient, highly developed art that involves a wide variety of equipment and procedures. A recent addition is direct push technology (DPT) in which desired data and/or samples from subterranean locations are obtained by instruments that are physically forced into the soil to penetrate it to precise testing depths. A prime example is cone penetrometer testing for determining soil types, consistency and density used for developing footing and pile foundation design criteria.
Typically, DPT comprises the hydraulic forcing of a push rod tipped with a pointed test member into the soil to the required depth. In testing for and obtaining samples of ground water or other fluids, DPT has been employed and "HYDROPUNCH" equipment has been developed using DPT (see Ground Water Management Review, Spring 1991, p. 101-106).
The present invention further advances the art of ground fluid sampling using direct push technology.
Ground water contamination and other environmental concerns about subterranian strata have placed new demands on existing technology for the sampling of subterranean waters or other fluids. For example, such sampling now requires that the acquired fluid sample be precisely confined to stratum from which it is designated to have been obtained. This may seem an obvious requirement, but prior known sampling methods often have resulted in samples contaiminated with fluids existing in strata other than the one designated, e.g., fluids encountered by the sampling device while reaching the datum stratum. Moreover, in order to meet this requirement using existing equipment, time consuming operations have been used that result in expensive additional labor costs, e.g., washing of push rod sections as they are withdrawn during retrevial of the desired sample.
Another problem encountered with known subterranean fluid sampling methods and apparatus is their failure to maintain the full sample volume as the sampling equipment is recovered for the subterranean site. Thus, deficiencies in such operations frequently result in major portions of the acquired sample being lost by leakage as the sampling equipment is retrieved.
The present invention addresses these known problems of prior subterranean fluid sampling methods and apparatus and provides unique solutions therefor.